URLs and their structure in Intro to Computing - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Identify the parts of a URL

Look at this URL:
https://www.example.com:8080/path/to/page?search=books#section2
Which part represents the port number?

A 8080

B section2

C /path/to/page

D https

💡 Hint

The port number comes after the domain and a colon (:).

In a URL, the port number is the number after the domain name separated by a colon. Here, 8080 is the port number.

❓ trace

intermediate

Trace URL components extraction

Given this URL:
http://blog.site.org/articles?id=123#comments
What is the value of the query string?

A 123

B id=123

C articles

D comments

💡 Hint

The query string comes after the question mark (?) in a URL.

The query string is the part after '?' and before '#'. Here, it is 'id=123'.

❓ Comparison

advanced

Compare URLs with and without port numbers

Which URL will connect to the default HTTP port?

A http://example.com/index.html

B http://example.com:443/index.html

C http://example.com:8080/index.html

D http://example.com:80/index.html

💡 Hint

Default HTTP port is 80 and usually omitted in URLs.

When no port is specified, HTTP uses port 80 by default. Option A omits the port, so it uses port 80.

❓ identification

advanced

Identify the fragment identifier in a URL

In the URL https://example.com/page.html#top, what does the fragment identifier represent?

A The domain name

B The path to the page

C The part after the hash (#) used to jump to a section

D The query parameters

💡 Hint

Fragment identifiers come after the '#' symbol.

The fragment identifier is the part after '#' and is used to jump to a specific section on the page.

🚀 Application

expert

Determine the full URL from parts

You have these URL parts:
- Protocol: https
- Domain: www.shop.com
- Port: 443
- Path: /products
- Query: category=books&sort=price
- Fragment: reviews

Which is the correct full URL?

A http://www.shop.com:443/products?category=books&sort=price#reviews

B https://www.shop.com:443/products?category=books&sort=price#reviews

C https://www.shop.com:80/products?category=books&sort=price#reviews

D https://www.shop.com/products?category=books&sort=price#reviews

💡 Hint

Port 443 is default for HTTPS and usually omitted.

Port 443 is the default for HTTPS, so it is usually not shown in the URL. The protocol must be https, not http.

Practice

1. Which part of a URL specifies the protocol used to access a resource?
https://www.example.com:8080/path?query=123#section

easy

A. www.example.com

B. 8080

C. https

D. /path

Solution

1. Step 1: Identify the scheme in the URL

   The scheme is the part before the first colon (:), which defines the protocol.

2. Step 2: Locate the scheme in the example URL

   In https://www.example.com:8080/path?query=123#section, the scheme is https.

3. Final Answer:

   https -> Option C

4. Quick Check:

   Scheme = https [OK]

Hint: Look before :// for the protocol name [OK]

Common Mistakes:

• Confusing domain with scheme
• Thinking port number is the protocol
• Selecting path as scheme

2. Which of the following is the correct syntax for a URL including a port number?

easy

A. http://example.com:80

B. http://:80example.com

C. http://example.com/80

D. http://example.com?80

Solution

1. Step 1: Understand port placement in URL syntax

   The port number comes after the domain, separated by a colon (:).

2. Step 2: Check each option for correct port syntax

   http://example.com:80 uses http://example.com:80, which correctly places port 80 after the domain with a colon.

3. Final Answer:

   http://example.com:80 -> Option A

4. Quick Check:

   Port follows domain with colon [OK]

Hint: Port number always follows domain with a colon [OK]

Common Mistakes:

• Placing port before domain
• Using slash instead of colon for port
• Adding port as query parameter

3. What is the full path and query part of this URL?
https://shop.example.com/products/item?id=12345&color=red#reviews

medium

A. /products/item?id=12345&color=red

B. /products/item#reviews

C. ?id=12345&color=red#reviews

D. /products/item?id=12345&color=red#reviews

Solution

1. Step 1: Identify path and query parts in the URL

   The path is the part after the domain up to the question mark (?), and the query is after the question mark up to the hash (#).

2. Step 2: Extract path and query from the example URL

   Path: /products/item, Query: ?id=12345&color=red. The fragment #reviews is not part of path or query.

3. Final Answer:

   /products/item?id=12345&color=red -> Option A

4. Quick Check:

   Path + Query = /products/item?id=12345&color=red [OK]

Hint: Path starts with /, query starts with ? [OK]

Common Mistakes:

• Including fragment (#reviews) in path or query
• Confusing query with fragment
• Ignoring query parameters

4. Identify the error in this URL:
ftp//files.example.com/downloads/file.zip

medium

A. Path should start with a question mark

B. Missing colon after scheme

C. Domain name is invalid

D. Port number is missing

Solution

1. Step 1: Check the scheme syntax

   The scheme must end with a colon (:), e.g., ftp:.

2. Step 2: Locate the error in the URL

   The URL has ftp// missing the colon after ftp. Correct form is ftp://.

3. Final Answer:

   Missing colon after scheme -> Option B

4. Quick Check:

   Scheme ends with : [OK]

Hint: Scheme must end with : before // [OK]

Common Mistakes:

• Ignoring missing colon in scheme
• Thinking domain is invalid
• Expecting port number always

5. You want to create a URL to access a user profile page with user ID 789 and show the 'settings' section. Which URL correctly uses path, query, and fragment?
Base URL: https://app.example.com

hard

A. https://app.example.com/user?id=789#settings?section=profile

B. https://app.example.com/user/789#settings?section=profile

C. https://app.example.com/user/789?section=settings#profile

D. https://app.example.com/user/789?section=settings#settings

Solution

1. Step 1: Understand URL parts for user profile

   The user ID should be part of the path (/user/789), the section to show is a query parameter (?section=settings), and the fragment points to a page section (#settings).

2. Step 2: Evaluate each option for correct structure

   https://app.example.com/user/789?section=settings#settings correctly places user ID in path, section in query, and fragment as #settings. Others mix fragment and query incorrectly or mismatch sections.

3. Final Answer:

   https://app.example.com/user/789?section=settings#settings -> Option D

4. Quick Check:

   Path + Query + Fragment correct [OK]

Hint: Path for ID, query for filters, fragment for page section [OK]

Common Mistakes:

• Swapping query and fragment parts
• Putting ID in query instead of path
• Using fragment with query parameters